Find the limit of $3x+1$ as $x$ approaches 0

Find the limit

$\lim_{x\to-1}\left(\frac{12x^3+12x^2}{x^4-x^2}\right)$

Find the limit

$\lim_{x\to1}\left(\frac{x^3-1}{4x^3-x-3}\right)$

Find the limit

$\lim_{x\to-3}\left(\frac{x^4-81}{x+3}\right)$

Find the limit

$\lim_{x\to-1}\left(\frac{12x^3+12x^2}{x^4-x^2}\right)$

Find the limit

$\lim_{x\to8}\left(\frac{x-8}{x^2-64}\right)$

Find the limit

$\lim_{x\to-3}\left(\frac{x^4-81}{x+3}\right)$

Find the limit

$\lim_{x\to-1}\left(\frac{12x^3+12x^2}{x^4-x^2}\right)$